//					Based On Lesson 6
//					=================
//
// All Code Is The Same, Except For Where I Have ( NEW )
// ( CHANGE ) Means I Have Changed The Line For This Tutorial.

#pragma comment(lib, "Glu32.lib")

#include <windows.h>											// Header File For Windows
#include <stdio.h>												// Header File For Standard Input/Output
#include <gl\gl.h>												// Header File For The OpenGL32 Library
#include <gl\glu.h>												// Header File For The GLu32 Library
#include "texture.h"											// Header File Containing Our Texture Structure ( NEW )

bool LoadTGA(Texture *, char *);								// Function Prototype For LoadTGA ( NEW )

HDC			hDC=NULL;											// Private GDI Device Context
HGLRC		hRC=NULL;											// Permanent Rendering Context
HWND		hWnd=NULL;											// Holds Our Window Handle
HINSTANCE	hInstance;											// Holds The Instance Of The Application

bool	keys[256];												// Array Used For The Keyboard Routine
bool	active=TRUE;											// Window Active Flag Set To TRUE By Default
bool	fullscreen=TRUE;										// Fullscreen Flag Set To Fullscreen Mode By Default

float	spin;													// Spin Variable

Texture texture[2];												// Storage For 2 Textures ( NEW )

LRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);			// Declaration For WndProc

int LoadGLTextures()											// Load Bitmaps And Convert To Textures
{
	int Status=FALSE;											// Status Indicator

	// Load The Bitmap, Check For Errors.
	if (LoadTGA(&texture[0], "Data/Uncompressed.tga") &&
		LoadTGA(&texture[1], "Data/Compressed.tga"))
	{
		Status=TRUE;											// Set The Status To TRUE

		for (int loop=0; loop<2; loop++)						// Loop Through Both Textures
		{
			// Typical Texture Generation Using Data From The TGA ( CHANGE )
			glGenTextures(1, &texture[loop].texID);				// Create The Texture ( CHANGE )
			glBindTexture(GL_TEXTURE_2D, texture[loop].texID);
			glTexImage2D(GL_TEXTURE_2D, 0, texture[loop].bpp / 8, texture[loop].width, texture[loop].height, 0, texture[loop].type, GL_UNSIGNED_BYTE, texture[loop].imageData);
			glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
			glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);

			if (texture[loop].imageData)						// If Texture Image Exists ( CHANGE )
			{
				free(texture[loop].imageData);					// Free The Texture Image Memory ( CHANGE )
			}
		}
	}
	return Status;												// Return The Status
}

GLvoid ReSizeGLScene(GLsizei width, GLsizei height)				// Resize And Initialize The GL Window
{
	if (height==0)												// Prevent A Divide By Zero By
	{
		height=1;												// Making Height Equal One
	}

	glViewport(0,0,width,height);								// Reset The Current Viewport

	glMatrixMode(GL_PROJECTION);								// Select The Projection Matrix
	glLoadIdentity();											// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);									// Select The Modelview Matrix
	glLoadIdentity();											// Reset The Modelview Matrix
}

int InitGL(GLvoid)												// All Setup For OpenGL Goes Here
{
	if (!LoadGLTextures())										// Jump To Texture Loading Routine ( NEW )
	{
		return FALSE;											// If Texture Didn't Load Return FALSE
	}

	glEnable(GL_TEXTURE_2D);									// Enable Texture Mapping ( NEW )
	glShadeModel(GL_SMOOTH);									// Enable Smooth Shading
	glClearColor(0.0f, 0.0f, 0.0f, 0.5f);						// Black Background
	glClearDepth(1.0f);											// Depth Buffer Setup
	glEnable(GL_DEPTH_TEST);									// Enables Depth Testing
	glDepthFunc(GL_LEQUAL);										// The Type Of Depth Testing To Do
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);			// Really Nice Perspective Calculations

	return TRUE;												// Initialization Went OK
}

int DrawGLScene(GLvoid)											// Here's Where We Do All The Drawing
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);			// Clear The Screen And The Depth Buffer
	glLoadIdentity();											// Reset The Modelview Matrix
	glTranslatef(0.0f,0.0f,-10.0f);								// Translate 20 Units Into The Screen

	spin+=0.05f;												// Increase Spin

	for (int loop=0; loop<20; loop++)							// Loop Of 20
	{
		glPushMatrix();											// Push The Matrix
		glRotatef(spin+loop*18.0f,1.0f,0.0f,0.0f);				// Rotate On The X-Axis (Up - Down)
		glTranslatef(-2.0f,2.0f,0.0f);							// Translate 2 Units Left And 2 Up

		glBindTexture(GL_TEXTURE_2D, texture[0].texID);			// ( CHANGE )
		glBegin(GL_QUADS);										// Draw Our Quad
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, 0.0f);
			glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, 0.0f);
			glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 0.0f);
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 0.0f);
		glEnd();												// Done Drawing The Quad
		glPopMatrix();											// Pop The Matrix

		glPushMatrix();											// Push The Matrix
		glTranslatef(2.0f,0.0f,0.0f);							// Translate 2 Units To The Right
		glRotatef(spin+loop*36.0f,0.0f,1.0f,0.0f);				// Rotate On The Y-Axis (Left - Right)
		glTranslatef(1.0f,0.0f,0.0f);							// Move One Unit Right

		glBindTexture(GL_TEXTURE_2D, texture[1].texID);			// ( CHANGE )
		glBegin(GL_QUADS);										// Draw Our Quad
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f, 0.0f);
			glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f, 0.0f);
			glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, -1.0f, 0.0f);
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, -1.0f, 0.0f);
		glEnd();												// Done Drawing The Quad
		glPopMatrix();											// Pop The Matrix
	}
	return TRUE;												// Keep Going
}

GLvoid KillGLWindow(GLvoid)										// Properly Kill The Window
{
	if (fullscreen)												// Are We In Fullscreen Mode?
	{
		ChangeDisplaySettings(NULL,0);							// If So Switch Back To The Desktop
		ShowCursor(TRUE);										// Show Mouse Pointer
	}

	if (hRC)													// Do We Have A Rendering Context?
	{
		if (!wglMakeCurrent(NULL,NULL))							// Are We Able To Release The DC And RC Contexts?
		{
			MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}

		if (!wglDeleteContext(hRC))								// Are We Able To Delete The RC?
		{
			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}
		hRC=NULL;												// Set RC To NULL
	}

	if (hDC && !ReleaseDC(hWnd,hDC))							// Are We Able To Release The DC
	{
		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hDC=NULL;												// Set DC To NULL
	}

	if (hWnd && !DestroyWindow(hWnd))							// Are We Able To Destroy The Window?
	{
		MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hWnd=NULL;												// Set hWnd To NULL
	}

	if (!UnregisterClass("OpenGL",hInstance))					// Are We Able To Unregister Class
	{
		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hInstance=NULL;											// Set hInstance To NULL
	}
}

/*	This Code Creates Our OpenGL Window.  Parameters Are:					*
 *	title			- Title To Appear At The Top Of The Window				*
 *	width			- Width Of The GL Window Or Fullscreen Mode				*
 *	height			- Height Of The GL Window Or Fullscreen Mode			*
 *	bits			- Number Of Bits To Use For Color (8/16/24/32)			*
 *	fullscreenflag	- Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE)	*/
 
BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
	GLuint		PixelFormat;									// Holds The Results After Searching For A Match
	WNDCLASS	wc;												// Windows Class Structure
	DWORD		dwExStyle;										// Window Extended Style
	DWORD		dwStyle;										// Window Style
	RECT		WindowRect;										// Grabs Rectangle Upper Left / Lower Right Values
	WindowRect.left=(long)0;									// Set Left Value To 0
	WindowRect.right=(long)width;								// Set Right Value To Requested Width
	WindowRect.top=(long)0;										// Set Top Value To 0
	WindowRect.bottom=(long)height;								// Set Bottom Value To Requested Height

	fullscreen=fullscreenflag;									// Set The Global Fullscreen Flag

	hInstance			= GetModuleHandle(NULL);				// Grab An Instance For Our Window
	wc.style			= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	// Redraw On Size, And Own DC For Window.
	wc.lpfnWndProc		= (WNDPROC) WndProc;					// WndProc Handles Messages
	wc.cbClsExtra		= 0;									// No Extra Window Data
	wc.cbWndExtra		= 0;									// No Extra Window Data
	wc.hInstance		= hInstance;							// Set The Instance
	wc.hIcon			= LoadIcon(NULL, IDI_WINLOGO);			// Load The Default Icon
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);			// Load The Arrow Pointer
	wc.hbrBackground	= NULL;									// No Background Required For GL
	wc.lpszMenuName		= NULL;									// We Don't Want A Menu
	wc.lpszClassName	= "OpenGL";								// Set The Class Name

	if (!RegisterClass(&wc))									// Attempt To Register The Window Class
	{
		MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}
	
	if (fullscreen)												// Attempt Fullscreen Mode?
	{
		DEVMODE dmScreenSettings;								// Device Mode
		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));	// Makes Sure Memory's Cleared
		dmScreenSettings.dmSize=sizeof(dmScreenSettings);		// Size Of The Devmode Structure
		dmScreenSettings.dmPelsWidth	= width;				// Selected Screen Width
		dmScreenSettings.dmPelsHeight	= height;				// Selected Screen Height
		dmScreenSettings.dmBitsPerPel	= bits;					// Selected Bits Per Pixel
		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

		// Try To Set Selected Mode And Get Results.  NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.
		if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
		{
			// If The Mode Fails, Offer Two Options.  Quit Or Use Windowed Mode.
			if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
			{
				fullscreen=FALSE;								// Windowed Mode Selected.  Fullscreen = FALSE
			}
			else
			{
				// Pop Up A Message Box Letting User Know The Program Is Closing.
				MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);
				return FALSE;									// Return FALSE
			}
		}
	}

	if (fullscreen)												// Are We Still In Fullscreen Mode?
	{
		dwExStyle=WS_EX_APPWINDOW;								// Window Extended Style
		dwStyle=WS_POPUP;										// Windows Style
		ShowCursor(FALSE);										// Hide Mouse Pointer
	}
	else
	{
		dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;			// Window Extended Style
		dwStyle=WS_OVERLAPPEDWINDOW;							// Windows Style
	}

	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);	// Adjust Window To True Requested Size

	// Create The Window
	if (!(hWnd=CreateWindowEx(	dwExStyle,							// Extended Style For The Window
								"OpenGL",							// Class Name
								title,								// Window Title
								dwStyle |							// Defined Window Style
								WS_CLIPSIBLINGS |					// Required Window Style
								WS_CLIPCHILDREN,					// Required Window Style
								0, 0,								// Window Position
								WindowRect.right-WindowRect.left,	// Calculate Window Width
								WindowRect.bottom-WindowRect.top,	// Calculate Window Height
								NULL,								// No Parent Window
								NULL,								// No Menu
								hInstance,							// Instance
								NULL)))								// Dont Pass Anything To WM_CREATE
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	static	PIXELFORMATDESCRIPTOR pfd=							// pfd Tells Windows How We Want Things To Be
	{
		sizeof(PIXELFORMATDESCRIPTOR),							// Size Of This Pixel Format Descriptor
		1,														// Version Number
		PFD_DRAW_TO_WINDOW |									// Format Must Support Window
		PFD_SUPPORT_OPENGL |									// Format Must Support OpenGL
		PFD_DOUBLEBUFFER,										// Must Support Double Buffering
		PFD_TYPE_RGBA,											// Request An RGBA Format
		bits,													// Select Our Color Depth
		0, 0, 0, 0, 0, 0,										// Color Bits Ignored
		0,														// No Alpha Buffer
		0,														// Shift Bit Ignored
		0,														// No Accumulation Buffer
		0, 0, 0, 0,												// Accumulation Bits Ignored
		16,														// 16Bit Z-Buffer (Depth Buffer)  
		0,														// No Stencil Buffer
		0,														// No Auxiliary Buffer
		PFD_MAIN_PLANE,											// Main Drawing Layer
		0,														// Reserved
		0, 0, 0													// Layer Masks Ignored
	};
	
	if (!(hDC=GetDC(hWnd)))										// Did We Get A Device Context?
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))				// Did Windows Find A Matching Pixel Format?
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	if(!SetPixelFormat(hDC,PixelFormat,&pfd))					// Are We Able To Set The Pixel Format?
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	if (!(hRC=wglCreateContext(hDC)))							// Are We Able To Get A Rendering Context?
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	if(!wglMakeCurrent(hDC,hRC))								// Try To Activate The Rendering Context
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	ShowWindow(hWnd,SW_SHOW);									// Show The Window
	SetForegroundWindow(hWnd);									// Slightly Higher Priority
	SetFocus(hWnd);												// Sets Keyboard Focus To The Window
	ReSizeGLScene(width, height);								// Set Up Our Perspective GL Screen

	if (!InitGL())												// Initialize Our Newly Created GL Window
	{
		KillGLWindow();											// Reset The Display
		MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;											// Return FALSE
	}

	return TRUE;												// Success
}

LRESULT CALLBACK WndProc(	HWND	hWnd,						// Handle For This Window
							UINT	uMsg,						// Message For This Window
							WPARAM	wParam,						// Additional Message Information
							LPARAM	lParam)						// Additional Message Information
{
	switch (uMsg)												// Check For Windows Messages
	{
		case WM_ACTIVATE:										// Watch For Window Activate Message
		{
			if (!HIWORD(wParam))								// Check Minimization State
			{
				active=TRUE;									// Program Is Active
			}
			else
			{
				active=FALSE;									// Program Is No Longer Active
			}

			return 0;											// Return To The Message Loop
		}

		case WM_SYSCOMMAND:										// Intercept System Commands
		{
			switch (wParam)										// Check System Calls
			{
				case SC_SCREENSAVE:								// Screensaver Trying To Start?
				case SC_MONITORPOWER:							// Monitor Trying To Enter Powersave?
				return 0;										// Prevent From Happening
			}
			break;												// Exit
		}

		case WM_CLOSE:											// Did We Receive A Close Message?
		{
			PostQuitMessage(0);									// Send A Quit Message
			return 0;											// Jump Back
		}

		case WM_KEYDOWN:										// Is A Key Being Held Down?
		{
			keys[wParam] = TRUE;								// If So, Mark It As TRUE
			return 0;											// Jump Back
		}

		case WM_KEYUP:											// Has A Key Been Released?
		{
			keys[wParam] = FALSE;								// If So, Mark It As FALSE
			return 0;											// Jump Back
		}

		case WM_SIZE:											// Resize The OpenGL Window
		{
			ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));		// LoWord=Width, HiWord=Height
			return 0;											// Jump Back
		}
	}

	// Pass All Unhandled Messages To DefWindowProc
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(	HINSTANCE	hInstance,						// Instance
					HINSTANCE	hPrevInstance,					// Previous Instance
					LPSTR		lpCmdLine,						// Command Line Parameters
					int			nCmdShow)						// Window Show State
{
	MSG		msg;												// Windows Message Structure
	BOOL	done=FALSE;											// Bool Variable To Exit Loop

	// Ask The User Which Screen Mode They Prefer
	if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
	{
		fullscreen=FALSE;										// Windowed Mode
	}

	// Create Our OpenGL Window
	if (!CreateGLWindow("NeHe & Evan 'terminate' Pipho's TGA Loading Tutorial",640,480,16,fullscreen))
	{
		return 0;												// Quit If Window Was Not Created
	}

	while(!done)												// Loop That Runs While done=FALSE
	{
		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))				// Is There A Message Waiting?
		{
			if (msg.message==WM_QUIT)							// Have We Received A Quit Message?
			{
				done=TRUE;										// If So done=TRUE
			}
			else												// If Not, Deal With Window Messages
			{
				TranslateMessage(&msg);							// Translate The Message
				DispatchMessage(&msg);							// Dispatch The Message
			}
		}
		else													// If There Are No Messages
		{
			// Draw The Scene.  Watch For ESC Key And Quit Messages From DrawGLScene()
			if ((active && !DrawGLScene()) || keys[VK_ESCAPE])	// Active?  Was There A Quit Received?
			{
				done=TRUE;										// ESC or DrawGLScene Signalled A Quit
			}
			else												// Not Time To Quit, Update Screen
			{
				SwapBuffers(hDC);								// Swap Buffers (Double Buffering)
			}

			if (keys[VK_F1])									// Is F1 Being Pressed?
			{
				keys[VK_F1]=FALSE;								// If So Make Key FALSE
				KillGLWindow();									// Kill Our Current Window
				fullscreen=!fullscreen;							// Toggle Fullscreen / Windowed Mode
				// Recreate Our OpenGL Window
				if (!CreateGLWindow("NeHe & Evan 'terminate' Pipho's TGA Loading Tutorial",640,480,16,fullscreen))
				{
					return 0;									// Quit If Window Was Not Created
				}
			}
		}
	}

	// Shutdown
	KillGLWindow();												// Kill The Window
	return (msg.wParam);										// Exit The Program
}

